Safety valve pipework

[IDCHAPPY]

I was always under the impression that this should be piped to outside?
Can it be taken to an internal drain if it had a tundish?

 

[jonny5isalive]

I've come across a few like this recently, god knows if it allowed. I don't like it. One didn't have a tundish even and the prv was discharged into the drain below a HepVO trap. Was on a Vaillant and so rang them to see and they said that that they do not allow it.

 

[IDCHAPPY]

I totally agree dude, I've seen 2 in 2 days, one of which I'm quoting for a boiler change on but if it's allowed ?
I guess I might phone ideal to see if they allow it.

 

[jonny5isalive]

Aside from that my mate was putting it in like that as it was specced on the new builds by the main plumbing contractor. On unvented tho rather than combi.

From the hepvo blurb


With an unvented hot water storage
system to connect a tundish outlet pipe to a drainage stack. This stops the omission of foul air from drainage systems into premises. Using the HepvO[emoji768] tundish adaptor kit, the connection from unvented hot water discharge appliances to soil stacks is simplified in systems with a temperature/pressure valve of no more than DN20. The kit reduces the number of fittings required, eliminating the need for a running adaptor.
This application is not recommended for combi or sealed boiler systems.
.

 

[Scott_D]

I think Worcester might allow it. Can anyone confirm?

 

[IDCHAPPY]

You'd think though,if you could run an unvented at up to 6bar/90+ C into HepVo traps combi's should be ok too?

 

[jonny5isalive]

Inhibitor, cleaner, crud is all i can see thats different.

Also what happens if the drains backed up or has been and theres crap stuck behind the bladder stopping it opening?

 

[lame plumber]

Inhibitor, cleaner, crud is all i can see thats different.

Also what happens if the drains backed up or has been and theres crap stuck behind the bladder stopping it opening?

they going to need dyno rod any how to clear their drains and blogged WCs

 

[GrahamM]

As far as I am aware this is a no-no from most if not all manufacturers.
Quite clear in BS must be run in to a safe visible position outside.
Most Manufactures do allow fitting of a remote PRV elsewhere on system though.

 

[stussy]

It is allowed on unvented with a tundish and a hepvo, but don't think it's allowed on boilers.

 

[AlexGas]

Quite clear in BS must be run in to a safe visible position outside.
Most Manufactures do allow fitting of a remote PRV elsewhere on system though.

There’s no word “outside” in the book. Outside all day long though.
Here it is:

COMMENTARY AND RECOMMENDATIONS ON 5.4.3
In addition to the requirements of 5.4.3.2 the pressure relief valve should
be located where its discharge is unlikely to cause damage to the premises.
It is essential that the pressure relief valve will not stick in the closed
position and that it will reseal.
A pressure relief valve is not necessary for an open system.

 

[AlexGas]

It should be located where its discharge is unlikely to cause damage to the premises.

 

[IDCHAPPY]

Yeah, I was pretty sure it *had* to go outside. With modern advancement in drainage and traps i was wondering why it wasn't possible to take it into a stack etc. Just seems odd as I'd be more worried about and unvented than a boiler PRV.

 

[AlexGas]

You, defo, got the point.

 

[the_ace]

My old flat in Newhaven the whole block were teed into the drain on ideal isars :32:, looks much better than staining the outside wall but doesn't sit well knowing there is potential for it to back up

 

[arran197]

From the experience I've gained on this issue, the prv is allowed to terminate in to a waste pipe. It should however, like has been said, have a tundish to provide a visual sign that it's discharging and should have a trap fitted downstream to prevent smells. Can you imagine running a prv pipe outside on a block of flats? The customer would never know the prv was discharging, so a tundish inside is far more appropriate.

It can also be an issue if the prv has been teed in to the condense pipe. The way around that is to have a sealed tundish to prevent pocs from escaping.

 

[AWheating]

its allowed, done in loads of flats. If your going to have to convince Building control there must be no other reasonable option. So if its straight forward to get it outside in a safe visable location then thats what needs to be done.